Method and apparatus for generating codeword, and method and apparatus for recovering codeword

ABSTRACT

Disclosed are a method and an apparatus for generating a codeword, and a method and an apparatus for recovering a codeword. An encoder calculates the number of punctured symbol nodes among symbol nodes included in a codeword, punctures symbol nodes located at even or odd number positions among the symbol nodes included in the codeword, calculates the number of symbol nodes which need to be additionally punctured on the basis of the calculated number of the symbol nodes to be punctured, classifies the symbol nodes, which need to be additionally punctured, into one or more punctured node groups on the basis of the calculated number of symbol nodes which need to be punctured, determines the locations on the codeword where the one or more punctured node groups are to be arranged, and punctures the symbol nodes included in the codeword which belong to the punctured node groups according to the determined locations. A transmission unit transmits the codeword.

CROSS-REFERENCE TO RELATED APPLICATION(S)

The present application claims priority under 35 U.S.C. § 365 toInternational Patent Application No. PCT/KR2015/003843 filed Apr. 16,2015, entitled “METHOD AND APPARATUS FOR GENERATING CODEWORD, AND METHODAND APPARATUS FOR RECOVERING CODEWORD”, and, through InternationalPatent Application No. PCT/KR2015/003843, to Korean Patent ApplicationNo. 10-2014-0046245 filed Apr. 17, 2014, each of which are incorporatedherein by reference into the present disclosure as if fully set forthherein.

TECHNICAL FIELD

The present disclosure relates to a method for transmitting andreceiving data in a wireless communication system, and moreparticularly, to a method and an apparatus for generating a codeword,and a method and an apparatus for recovering a codeword.

BACKGROUND ART

In channel coding technology, it is important to make it possible tofreely and variably adjust the code rate of a channel. For example, inthe case of a wireless communication system, a receiver measures achannel state and transmits channel state information to a sender, andthe sender determines the code rate of a code to be used on the basis ofthe received information. In this case, codes having various code ratesare required in accordance with the channel state of the receiver.Accordingly, it is inevitably required to provide a method for designinga code having a variable code rate.

In the case of designing a code having a variable code rate throughpuncturing using the existing LDPC code, a puncturing pattern has beendesigned on the basis of the concept of a k-Step Recoverable(hereinafter, kSR) node that is information about the number of times ofdecoding for a punctured symbol node to receive a reliable messageduring a repetitive decoding process. According to this designingmethod, the puncturing pattern is designed so that the maximum value ofa recoverable step of a puncturing node becomes a value as small aspossible.

In the case of designing a puncturing pattern of a BICM-ID structureusing an Irregular Repetition (hereinafter, IR) code, in the same manneras the LDPC code, it may be first considered to use the concept of thekSR node.

However, according to the above-described method, it is easy to find thepuncturing pattern that corresponds to the respective code rates, but itis general that the puncturing pattern having a low code rate does notbecome a subset of the puncturing pattern having a high code rate. Thismay cause a problem when a rate-compatible structure that supportsvarious code rates with one code is designed.

DISCLOSURE OF INVENTION Technical Problem

The present disclosure has been made in order to solve the aboveproblems, and an aspect of the present disclosure provides a method andan apparatus for generating a codeword, and a method and an apparatusfor recovering a codeword, which can enable a normal operation to beperformed even in the case of performing puncturing at a high code ratein a Bit-Interleaved Coded Modulation with Iterative Decoding (BICM-ID)structure based on an IR code.

Another aspect of the present disclosure provides a method and anapparatus for generating a codeword, and a method and an apparatus forrecovering a codeword, which can facilitate the design of arate-compatible structure that can support various code rates.

Solution to Problem

In one aspect of the present disclosure, a method for generating acodeword includes: calculating the number of punctured symbol nodesamong symbol nodes included in a codeword; puncturing symbol nodeslocated at even or odd number positions among the symbol nodes includedin the codeword; calculating the number of symbol nodes which need to beadditionally punctured on the basis of the calculated number of thesymbol nodes to be punctured; classifying the symbol nodes, which needto be additionally punctured, into one or more punctured node groups onthe basis of the calculated number of symbol nodes which need to bepunctured; determining the locations on the codeword where the one ormore punctured node groups are to be arranged; and puncturing the symbolnodes included in the codeword which belong to the punctured node groupsaccording to the determined locations.

In another aspect of the present disclosure, an apparatus for generatinga codeword includes: an encoder which calculates the number of puncturedsymbol nodes among symbol nodes included in a codeword, punctures symbolnodes located at even or odd number positions among the symbol nodesincluded in the codeword, calculates the number of symbol nodes whichneed to be additionally punctured on the basis of the calculated numberof the symbol nodes to be punctured, classifies the symbol nodes, whichneed to be additionally punctured, into one or more punctured nodegroups on the basis of the calculated number of symbol nodes which needto be punctured, determines the locations on the codeword where the oneor more punctured node groups are to be arranged, and punctures thesymbol nodes included in the codeword which belong to the punctured nodegroups according to the determined locations; and a transmission unitwhich transmits the codeword.

In still another aspect of the present disclosure, a method forrecovering a codeword includes: receiving a codeword, wherein thereceived codeword is generated by puncturing symbol nodes located ateven or odd number positions among symbol nodes included in thecodeword, classifying the symbol nodes, which need to be additionallypunctured, into one or more punctured node groups, and puncturing thesymbol nodes which belong to the punctured node groups according to thelocations on the codeword where the one or more punctured node groupsare arranged; demodulating the received codeword; and decoding thedemodulated codeword.

In yet still another aspect of the present disclosure, a receiverincludes: a reception unit configured to receive a codeword; ademodulation unit configured to demodulate the received codeword; and adecoder configured to decode the demodulated codeword, wherein thereceived codeword is generated by puncturing symbol nodes located ateven or odd number positions among symbol nodes included in thecodeword, classifying the symbol nodes, which need to be additionallypunctured, into one or more punctured node groups, and puncturing thesymbol nodes which belong to the punctured node groups according to thelocations on the codeword where the one or more punctured node groupsare arranged.

Advantageous Effects of Invention

According to the method and the apparatus for generating a codeword, andthe method and the apparatus for recovering a codeword according to thepresent disclosure, it is possible to generate the puncturing patternthat can perform the normal operation even in the case of performing thepuncturing at a high code rate in the Bit-Interleaved Coded Modulationwith Iterative Decoding (BICM-ID) structure based on the IR code, and itis possible to easily generate the codeword having the rate-compatiblestructure that can support various code rates.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating the configuration of atransmission device according to a preferred embodiment of the presentdisclosure;

FIG. 2 is a block diagram illustrating the configuration of an encoderaccording to a preferred embodiment of the present disclosure;

FIG. 3 is a diagram illustrating the structure of an internal encoderaccording to a preferred embodiment of the present disclosure;

FIG. 4 is a graph illustrating a decoding trajectory;

FIG. 5 is a graph explaining the function of a doping symbol;

FIG. 6 is a diagram illustrating an arrangement of a doping symbolaccording to a preferred embodiment;

FIG. 7 is a diagram illustrating an arrangement of a doping symbolaccording to another preferred embodiment;

FIG. 8 is a diagram explaining a method for puncturing a codewordaccording to an embodiment of the present disclosure;

FIG. 9 is a diagram explaining a method for puncturing a codewordaccording to another embodiment of the present disclosure;

FIG. 10 is a block diagram illustrating the configuration of a receptiondevice according to a preferred embodiment of the present disclosure;

FIG. 11 is a block diagram illustrating the configuration of a decoderaccording to a preferred embodiment of the present disclosure;

FIG. 12 is a flowchart illustrating performing processes of a method forgenerating a codeword according to a preferred embodiment of the presentdisclosure;

FIG. 13 is a flowchart illustrating performing processes of a method forpuncturing a codeword according to a preferred embodiment of the presentdisclosure;

FIG. 14 is a flowchart illustrating performing processes of a method forgenerating a codeword according to another preferred embodiment of thepresent disclosure;

FIG. 15 is a flowchart illustrating performing processes of a method fordecoding a codeword according to a preferred embodiment of the presentdisclosure;

FIG. 16 is a graph illustrating the performance of a method forgenerating a codeword; and

FIG. 17 is another graph illustrating the performance of a method forgenerating a codeword.

MODE FOR THE INVENTION

Hereinafter, preferred embodiments of the present disclosure will bedescribed in detail with reference to the accompanying drawings. Indescribing the present disclosure, detailed description of well-knownfunctions or configurations incorporated herein will be omitted if it isjudged that such description unnecessarily obscures the subject matterof the present disclosure. This is to avoid obscuring the subject matterof the present disclosure and to transfer the same more accuratelythrough omission of the unnecessary description.

For the same reason, in the accompanying drawings, some constituentelements are exaggerated, omitted, or roughly illustrated. Further,sizes of some constituent elements may not completely reflect the actualsizes thereof. In the drawings, the same drawing reference numerals areused for the same elements across various figures.

In describing embodiments of the present disclosure in detail, an LTEsystem and an LTE-Advanced (LTE-A) system will be exemplified. However,the main subject matter of the present disclosure can be applied toother communication systems adopting similar technology with slightmodifications within a range that does not greatly deviate from thescope of the present disclosure, according to the judgment of a personskilled in the art to which the present disclosure pertains.

FIG. 1 is a block diagram illustrating the configuration of atransmission device according to a preferred embodiment of the presentdisclosure.

Referring to FIG. 1, a transmission device 100 according to the presentdisclosure may include an encoder 110, a modulation unit 120, atransmission unit 130, a control unit 140, and a reception unit 150.

The transmission device 100 according to the present disclosure mayinclude at least one of a Base Station (BS) (or evolved Node B (eNB) orE-UTRAN Node B), a Relay Node (RN), and a terminal (or User Equipment(UE), Mobile Station (MS), or Subscriber Station (SS)).

The encoder 110 encodes data and generates a codeword. The encoder 110may generate a codeword in a Bit-Interleaved Coded Modulation withIterative Decoding (BICM-ID) method using a binary code. The BICM-IDmethod used in the present disclosure is composed of an outer code basedon an irregular repetition code and an inner code based on a trelliscode. The BICM-ID method shows a similar performance to the performanceof a non-binary LDPC code, and has decoding complexity that is lowerthan the decoding complexity of the non-binary LDPC code. This methodreceives a message intended to be transmitted in the unit of a bit, andrepeats all bits as many as a predetermined number of times. In thiscase, the number of repetitions for each bit may not be uniform. Theencoder 110 optionally mixes repeated bit strings by making the repeatedbit strings pass through an interleaver, and performs grouping thereofas many as the predetermined number of times. The encoder encodes thebit strings that come out as the result of the grouping using an innerencoder, and outputs a codeword to the modulation unit 120.

Unlike the structure of a general LDPC code, the BICM-ID structure hastwo check nodes connected to a symbol node. Accordingly, ifnon-punctured nodes are arranged around a punctured node, reliablemessages can be directly obtained from both sides to cause fastconvergence speed. After several iterations in iterative decoding, allthe non-punctured nodes around the punctured nodes have messages of highreliability, and these punctured nodes contribute to the recovery of themessages in consecutive puncturing sections together with thenon-punctured nodes.

The encoder 110 may insert doping information into the codeword. Thedoping information means information already known by both the senderand the receiver to succeed in decoding of the codeword. The dopinginformation may include doping symbols. The doping symbol means a symbolvalue pre-engaged between the transmission device and the receptiondevice and location information of the symbol value in the codeword thatis generated by the transmission device. The encoder 110 inserts thedoping symbols into the codeword.

The encoder 110 may puncture the codeword into which the doping symbolsare inserted. The encoder 110 may puncture the codeword on the basis ofthe doping information included in the codeword, perform the puncturingso that lots of non-punctured nodes are arranged in front and in therear of punctured nodes, and perform the puncturing so that the numberof consecutively punctured nodes does not become too large.

The modulation unit 120 may modulate the codeword that is output by theencoder 110. The modulation unit 120 may be a FQAM modulator, and maymodulate the codeword in a FQAM method to generate a modulation signal.The FQAM is a hybrid modulation method in which QAM and FSK are combinedwith each other, and has the characteristics to make an interferencesignal non-Gaussian in a similar manner to the FSK. Further, the FQAMsimultaneously applies the QAM method, and thus greatly improves thespectral efficiency in comparison to the FSK method.

In order to obtain higher data throughput through application of theFQAM method, a channel code that suits the corresponding modulationmethod. As the existing QAM series modulation method, a binary turbocode based BICM method has been mainly used. However, in the case ofusing the above-described method in the FOAM method, it becomesimpossible to obtain the performance that approaches a channel capacitorcorresponding to a theoretical limit value. Accordingly, in order tosolve this problem, a BICM-ID method based on a binary repetition codeis used to obtain the performance that approaches the theoretical limitvalue.

As methods that can achieve the channel capacity when the FQAMmodulation method is applied, there exist a Coded Modulation (CM) methodusing a non-binary LDPC code and a Bit-Interleaved Coded Modulation withIterative Decoding (BICM-ID) method using a binary code. The BICM-IDmethod used in the present disclosure is composed of an outer code basedon an irregular repetition code and an inner code based on a trelliscode. This method shows a similar performance to the performance of anon-binary LDPC code, and has decoding complexity that is lower than thedecoding complexity of the non-binary LDPC code. This method receives amessage intended to be transmitted in the unit of a bit, and repeats allbits as many as a predetermined number of times. In this case, thenumber of repetitions for each bit may not be uniform. The repeated bitstrings are optionally mixed through an interleaver, and are grouped asmany as the predetermined number of times. The bit strings that come outas the result of the grouping are encoded using an inner encoder, and amodulation signal is obtained by inputting this codeword to a FQAMmodulator.

The transmission unit 130 may transmit the codeword that is modulated bythe modulation unit 120 to the reception device.

The control unit 140 executes a command and performs an operationrelated to the transmission device 100. For example, using the command,the control unit 140 may control input/output and datareception/processing between components of the transmission device 100.The control unit 140 may execute the command related to informationreceived from the input device.

The control unit 140 executes a program code together with the operatingsystem of the transmission device 100, and generates and uses data. Thecontrol unit 140 may control the operations of the encoder 110, themodulation unit 120, the transmission unit 130, and the reception unit150. In a partial embodiment, the control unit 140 may perform thefunctions of the encoder 110 and the modulation unit 120. Since theoperating system is generally known, the detailed description thereofwill be omitted. For example, the operating system may be Window seriesOS, UNIX, Linux, Palm OS, DOS, Android, or Macintosh. The operatingsystem, other computer codes, and data may exist in a storage device ofthe transmission device 100 that is connected to the control unit 140 tooperate.

The control unit 140 may be implemented on a single chip, a plurality ofchips, or a plurality of electrical components. For example, variousarchitectures including a dedicated or embedded processor, a singlepurpose processor, a controller, an ASIC, or the like may be used forthe control unit 140.

The control unit 140 may recognize a user action, and may control thetransmission device 100 on the basis of the recognized user action.Here, the user action may include selection of a physical button of thetransmission device, execution of a predetermined gesture or selectionof a soft button on a touch screen display, execution of a predeterminedgesture that is recognized from an image captured by an image capturingdevice, and execution of predetermined vocalization that is recognizedthrough voice recognition. The gesture may include a touch gesture and aspatial gesture.

The reception unit 150 receives data from another transmission device.The data may include information on the result of measurement of thechannel state. The control unit 140 may adjust the code rate of thecodeword on the basis of the information, and may adjust a puncturingmethod. The reception unit 150 may receive a control signal from anothertransmission device through a wireless channel.

As a partial embodiment, the transmission device 100 may be connected toa base station or nodes (e.g., SGW and MME) on a core network through awired interface (not illustrated) to transmit and receive a signal.

FIG. 2 is a block diagram illustrating the configuration of an encoderaccording to a preferred embodiment of the present disclosure.

Referring to FIG. 2, an encoder 110 may include a binary encoder 210, aninterleaver 220, and an inner encoder 230.

The binary encoder 210 encodes data (or a message) and generates acodeword. The binary encoder 210 may encode the data using a binarycode. The binary encoder 210 may receive the data from the control unit140 in the unit of a bit, and may generate the codeword throughrepetition of all bits as many as a predetermined number of times. Here,the number of repetitions for each bit may not be uniform. The codewordthat is output from the binary encoder 210 may be a binary data stream.

The interleaver 220 interleaves the codeword that is generated by thebinary encoder 210. The interleaver 220 may rearrange binary datastreams output from the binary encoder 210, and may tie up apredetermined number of binary data streams into a group. Further, theinterleaver 220 may output bit strings that are tied up into a group tothe inner encoder 230.

The inner encoder 230 inserts doping symbols into the codeword that isoutput from the interleaver 220. Here, the codeword may be bit stringsthat are tied up into a group. The inner encoder 230 may insert thedoping symbols into the codeword after encoding the codeword that isoutput from the interleaver 220.

The inner encoder 230 punctures the codeword into which the dopingsymbols are inserted, and outputs the punctured codeword to themodulation unit 120.

In order to perform the puncturing, the inner encoder 230 calculates thenumber of punctured symbol nodes among symbol nodes included in thecodeword. As a partial embodiment, the inner encoder 230 may calculatethe number of the punctured symbol nodes among the symbol nodes includedin the codeword on the basis of the current code rate and a target coderate of the codeword.

The inner encoder 230 confirms whether the target code rate of thegenerated codeword is smaller than 2/3, and if the target code rate issmaller than 2/3, the inner encoder 230 punctures the symbol nodesincluded in the codeword so that the punctured nodes are uniformlyarranged on the codeword. The target code rate may be a code rate of thecodeword that is output to the modulation unit 120.

If the target code rate is not smaller than 2/3, the inner encoder 230punctures symbol nodes located at even or odd number positions amongsymbol nodes included in the codeword. The symbol nodes to be puncturedamong the symbol nodes located at even or odd number positions may bedetermined on the basis of the locations of the doping symbols includedin the codeword.

The inner encoder 230 calculates the number of symbol nodes which needto be additionally punctured on the basis of the calculated number ofthe symbol nodes to be punctured, and classifies the symbol nodes, whichneed to be additionally punctured, into one or more punctured nodegroups on the basis of the number of symbol nodes which need to beadditionally punctured.

As a partial embodiment, the inner encoder 230 may classify the symbolnodes into one or more punctured node groups on the basis of at leastone of the size and the number of symbol bands of the codeword. Here,the symbol band means a set of a predetermined number of consecutivecode symbols including one doping symbol.

As a partial embodiment, the inner encoder 230 may classify the symbolnodes into one or more punctured node groups on the basis of at leastone of the size and the number of symbol bands of the codeword and thesize of the punctured node group determined according to a predeterminedvalue. The sizes of at least two punctured node groups among the one ormore punctured node groups may be equal to each other.

The inner encoder 230 determines the locations on the codeword where theone or more classified punctured node groups are to be arranged, andpunctures the symbol nodes included in the codeword which belong to thepunctured node groups according to the determined locations. As apartial embodiment, each of the one or more punctured node groups may bearranged in the center of the symbol band of the codeword.

Further, a plurality of punctured node groups may be arranged on atleast one of the symbol bands of the codeword. The number of puncturednode groups arranged on the symbol band may be determined on the basisof at least one of the doping symbol and the target code rate of thecodeword, and the number of punctured node groups arranged on at leastone of the symbol bands of the codeword may be different from the numberof punctured node groups arranged on another symbol band.

As a partial embodiment, for conversion of a first target code rate intoa second target code rate, the inner encoder 230 may calculate thenumber of punctured nodes to be unpunctured in the codeword punctured atthe first target code rate and may unpuncture the punctured nodes in thecodeword according to the calculated number of punctured nodes. Here,the punctured nodes that belong to the punctured node group may be firstunpunctured. The first target code rate and the second target code ratemay be different from each other, and the second target code rate may behigher than the first target code rate.

As a partial embodiment, the encoder 110 may further include apuncturing unit, and the puncturing unit may puncture the codeword intowhich the doping symbols are inserted in place of the inner encoder 230.

FIG. 3 is a diagram illustrating the structure of an internal encoderaccording to a preferred embodiment of the present disclosure.

Referring to FIG. 3, the structural diagram 300 shows the structure ofan inner encoder 230 according to an embodiment. The inner encoder 230may encode a codeword (C0, C1, C2, C3, C4, C5, C6, C7) output from theinterleaver 220 to a codeword (b0, b1, b2, b3). The inner encoder 230generates α0 on the basis of symbols C0 and C1, generates α1 on thebasis of symbols C2 and C3, generates α2 on the basis of symbols C4 andC5, and generates α3 on the basis of symbols C6 and C7. Symbol b0 may begenerated on the basis of the symbol α0 and a delay S, and the delay Smay delay the symbols generated on the basis of α0, α1, α2, and α3.Symbols b1, b2, and b3 may be generated from α1, α2, and α3.

FIG. 4 is a graph illustrating a decoding trajectory.

Referring to FIG. 4, in the graph 400, a decoding trajectory 410indicates a trajectory of iterative decoding at 0.1 dB. The decodingtrajectory 410 indicates that decoding is not performed over 0.2.

A decoding trajectory 420 indicates a trajectory of iterative decodingat 0.8 dB. The decoding trajectory 420 indicates a process in whichdecoding is gradually increased to be completed between a first decoderand a second decoder.

As can be known from the decoding trajectories 410 and 420, the decodingmay fail at a specific dB or less.

FIG. 5 is a graph explaining the function of a doping symbol.

Referring to FIG. 5, the doping symbol may be inserted into the codewordby the inner encoder 230, and may be inserted into a pre-engagedlocation between the transmission device and the reception device. Thedoping symbol may be used as information that helps a decoder accordingto the present disclosure to operate.

In the graph 500, a line 510 indicates a decoding trajectory of an innercode, and a line 520 indicates a decoding trajectory of a designed outercode. The doping symbol serves to heighten a start point of the decodingas high as the size 530 thereof. Accordingly, the transmission deviceand the reception device according to the present disclosure can preventthe iterative decoding from failing using the doping symbol.

The inner decoder 230 may determine the rate of the doping symbol to beinserted into the codeword according to the length of the codeword. Asan example, the inner encoder 230 may determine the rate of the dopingsymbol at the rate in the range of 1% to 5% of the whole codeword.

FIG. 6 is a diagram illustrating an arrangement of a doping symbolaccording to a preferred embodiment.

Referring to FIG. 6, point 601, point 603, point 605, and point 607indicate locations in the codeword into which doping symbols areinserted. As illustrated in FIG. 6, the inner encoder 230 mayconcentratedly arrange the doping symbols in a specific section of thecode.

FIG. 7 is a diagram illustrating an arrangement of a doping symbolaccording to another preferred embodiment.

Referring to FIG. 7, point 701, point 703, point 705, and point 707indicate locations in the codeword into which doping symbols areinserted. As illustrated in FIG. 7, the inner encoder 230 maydispersedly arrange the doping symbols in a specific section of thecode.

FIG. 8 is a diagram explaining a method for puncturing a codewordaccording to an embodiment of the present disclosure.

Referring to FIG. 8, in the case of encoding a codeword having thecurrent code rate of 1/3 at a target code rate r(=1/R, R≥2/3), an indexi of the symbol node of the codeword is defined as in mathematicalexpression 1 below, and it is assumed that it starts from 0.i=sD+j  [Mathematical Expression 1]

The inner encoder 230 punctures the symbol node if the index i of thesymbol node satisfies the following basic puncturing condition.j=2k,k=0,1, . . . ,D/2−1 if s≤N _(D)−1 and k=0, . . . ,└N _(D)/2┘−1 ifs=N _(D)  (Basic puncturing condition)

Here, D denotes the number of symbols included in a symbol band 811, andN_(D) denotes the number of symbols of the last symbol band 831. Thelast symbol band does not include the doping symbol.

The inner encoder 230 punctures the symbol node if the index i of thesymbol node satisfies the following additional puncturing condition 1.sD+η≤i≤sD+η+2(N _(p)−1),s∈T _(p)sD+η≤i≤sD+η+2(N _(p)′−1),s∈T _(p)′  (Additional puncturing condition 1)

Here, η is an odd number that satisfies 1≤η≤D−2N′_(p)−1, and the aboveexpressions are established with respect to all s.

N_(p) is defined as in mathematical expression 2 below.

$\begin{matrix}{N_{p} = \lfloor {{( {\frac{1}{2} - \frac{R}{3}} )\frac{N}{N_{D}}} + \frac{1}{2}} \rfloor} & \lbrack {{Mathematical}\mspace{14mu}{Expression}\mspace{14mu} 2} \rbrack\end{matrix}$

N_(p)′ is defined as in mathematical expression 3 below.N _(p) ′=N _(p)+1  [Mathematical Expression 3]

T_(p) and T_(p)′ are disjoint lower sets of an index set {0, 1, . . . ,N_(D)} that satisfies mathematical expression 4 below.

$\begin{matrix}{{{N_{p} \cdot {T_{p}}} + {N_{p}^{\prime} \cdot {T_{p}^{\prime}}}} = {{( {\frac{1}{2} - \frac{R}{3}} )N} + \frac{N_{D}}{2}}} & \lbrack {{Mathematical}\mspace{14mu}{Expression}\mspace{14mu} 4} \rbrack\end{matrix}$

Further, if N_(D)≤D, it is assumed that N_(D)∈T_(p), and if N_(D)>D, itis assumed that N_(D)∈T_(p)′.

As an embodiment, a case where a code having a code rate of 10/31 ispunctured to 5/6 will be described hereinafter. The inner decoder 230first punctures symbol nodes one after another. For convenience, theinner decoder 230 punctures all odd-numbered symbol nodes. Even throughsuch puncturing, the code rate becomes 20/31, and thus a desired coderate is unable to be obtained. In this case, in order to obtain adesired code rate, the punctured symbol nodes are consecutively arrangedas in consecutive puncturing sections 815 and 835. Here, the puncturednode group may be located in the consecutive puncturing sections 815 and835.

In the case of the code rate of 5/6, it is proper that the size of theconsecutive puncturing sections corresponds to about 13 sections. Theinner encoder 230 may set the consecutive puncturing sections so that alarge number of doping symbols are not punctured in full considerationof the locations of the doping symbols. If a puncturing pattern isobtained as described above, a stepping puncturing section in whichsymbol nodes are punctured one after another and a consecutivepuncturing section in which several symbol nodes are consecutivelypunctured appear repeatedly.

The method for puncturing a codeword as illustrated in FIG. 8 has thefollowing advantages. According to the puncturing using the existing kSRconcept, performance deterioration appears remarkably at a high coderate. However, if the puncturing pattern is designed in the method forpuncturing a codeword as illustrated in FIG. 8, a code that suits thecorresponding code rate can be designed. Further, according to themethod for puncturing a codeword as illustrated in FIG. 8, arate-compatible structure that supports various code rates can bedesigned more easily. In detail, a puncturing pattern that suits a highcode rate (first target code rate) is first designed. Further, in thecase of intending to obtain a pattern having a code rate (second targetcode rate) that is lower than the first target code rate, nodes locatedat even number positions among nodes that belong to the consecutivepuncturing sections (punctured node group) are punctured in turn until adesired code rate is obtained. In this case, better performance can beobtained by making unpunctured nodes uniformly distributed in the wholeconsecutive puncturing sections if possible. The code designed asdescribed above does not show great performance deterioration incomparison to the puncturing pattern that is optimal at the secondtarget code rate.

FIG. 9 is a diagram explaining a method for puncturing a codewordaccording to another embodiment of the present disclosure.

Referring to FIG. 9, in the case of encoding a codeword having thecurrent code rate of 1/3 at a target code rate r(=1/R, r≥2/3), an indexi of the symbol node of the codeword is defined as in mathematicalexpression 1 as described above, and it is assumed that it starts from0.

The inner encoder 230 punctures the above-described symbol node if theindex i of the symbol node satisfies the basic puncturing condition.

The inner encoder 230 punctures the symbol node if the index i of thesymbol node satisfies the following additional puncturing conditions 2to 4.

If the following additional puncturing condition 2 is satisfied withrespect to the index i of the symbol node that satisfies ν_(s)=1 in thecase where ν_(s)≤1 is given with respect to all s, the inner encoder 230punctures the above-described symbol node.sD+η≤i≤sD+η+2(τ−1)  (Additional puncturing condition 2)

Here, η is an odd number that satisfies 1≤η≤D−2N_(p)′−1.

If the following additional puncturing condition 3 is satisfied withrespect to the index i of the symbol node that satisfies ν_(s)=1 in thecase where ν_(s)≥1 is given with respect to all s, the inner encoder 230punctures the above-described symbol node.sD+η ₁ ≤i≤sD+η ₁+2(τ−1)  (Additional puncturing condition 3)

Further, if the following condition is satisfied with respect to theindex i of the symbol node that satisfies the following additionalpuncturing condition 4 in the case where ν_(s)>1 is given with respectto all s, the inner encoder 230 punctures the above-described symbolnode.sD+η _(k) ≤i≤sD+η _(k)+2(τ−1)  (Additional puncturing condition 4)

Here, k denotes an integer in the range of 1 to ν_(s), and indicatesη_(k+1)−η_(k)=└D/ν_(s)┘−(2τ+1), η₀=0. Further, ν_(s) is defined as inthe following mathematical expression 5.ν_(s) =└s·ν _(p)┘−└(s−1)·ν _(p)┘  [Mathematical Expression 5]

ν _(p) is defined as in the following mathematical expression 6.ν _(p)=(ν_(p)=ν_(N) _(D) )/N _(D)  [Mathematical Expression 6]

ν_(p) is defined as in the following mathematical expression 7.

$\begin{matrix}{v_{p} = \lfloor {\frac{1}{\tau} \cdot ( {{( {1 - \frac{R}{3}} )N} + N_{D}} )} \rfloor} & \lbrack {{Mathematical}\mspace{14mu}{Expression}\mspace{14mu} 7} \rbrack\end{matrix}$

Here, τ means a figure that makes the number of consecutive puncturedsymbol nodes become 2τ+1.

ν_(N) _(D) is defined as follows.

If ν_(p)≥N_(D), and N_(D)>2D, it is defined that ν_(N) _(D) =2.

If ν_(p)≥N_(D), and D<N_(D)≤2D, it is defined that ν_(N) _(D) =1.

If ν_(p)≥N_(D), and N_(D)≤D, it is defined that ν_(N) _(D) =0.

If ν_(p)<N_(D), and N_(D)>2D, it is defined that ν_(N) _(D) =1.

If ν_(p)<N_(D), and N_(D)≤2D, it is defined that ν_(N) _(D) =0.

Here, if the number of doping symbols is set to 1% to 5% of the codesymbol, ν_(s) does not typically exceed 2. In most cases, ν_(s) becomes1 or 0.

A punctured node group 921 is arranged on symbol bands. According to theadditional puncturing condition 2, a plurality of punctured node groupsmay be arranged on the symbol bands 911 and 921. The number of puncturednode groups arranged on the symbol band 911 may be different from thenumber of punctured node groups arranged on the symbol band 921. In thecase where the number of doping symbols is small and the code rate ishigh, a plurality of punctured node groups may be arranged on one symbolband.

If the N_(D) value is large, the punctured node group may be arrangedeven on the last symbol band 931.

FIG. 10 is a block diagram illustrating the configuration of a receptiondevice according to a preferred embodiment of the present disclosure.

Referring to FIG. 10, a reception device 1000 according to the presentdisclosure may include a reception unit 1010, a demodulation unit 1020,a decoder 1030, a control unit 1040, and a transmission unit 1050.

The reception device may include at least one of a Base Station (BS) (orevolved Node B (eNB) or E-UTRAN Node B), a Relay Node (RN), and aterminal (or User Equipment (UE) or Mobile Station (MS) or SubscriberStation (SS)).

As a partial embodiment, the transmission device 100 of FIG. 1 and thereception device 1000 may be implemented as one device.

The reception unit 1010 receives a codeword from the transmission device100. The codeword may include a control signal and data. The receivedcodeword may be generated by puncturing symbol nodes located at even orodd number positions among symbol nodes included in the codeword,classifying the symbol nodes, which need to be additionally punctured,into one or more punctured node groups, and puncturing the symbol nodeswhich belong to the punctured node groups according to the locations onthe codeword where the one or more punctured node groups are arranged.

The demodulation unit 1020 demodulates the codeword received by thereception unit 1010.

The decoder 1030 decodes the codeword demodulated by the demodulationunit 1020. The decoder 1030 may decode the codeword using doping symbolsincluded in the codeword. As an example, the doping symbol may be usedas information that helps an iterative decoder to operate. Here, theiterative decoder may be an iterative decoder of an IRPA code.

The control unit 1040 executes a command and performs an operationrelated to the reception device 1000. For example, using the command,the control unit 1040 may control input/output and datareception/processing between components of the reception device 1000.The control unit 1040 may execute the command related to informationreceived from the input device.

The control unit 1040 executes a program code together with theoperating system of the reception device 1000, and generates and usesdata. The control unit 1040 may control the operations of the receptionunit 1010, the demodulation unit 1020, the decoder 1030, and thetransmission unit 1050. In a partial embodiment, the control unit 1040may perform the functions of the demodulation unit 1020 and the decoder1030. Since the operating system is generally known, the detaileddescription thereof will be omitted. For example, the operating systemmay be Window series OS, UNIX, Linux, Palm OS, DOS, Android, orMacintosh. The operating system, other computer codes, and data mayexist in a storage device of the reception device 1000 that is connectedto the control unit 1040 to operate.

The control unit 1040 may be implemented on a single chip, a pluralityof chips, or a plurality of electrical components. For example, variousarchitectures including a dedicated or embedded processor, a singlepurpose processor, a controller, an ASIC, or the like may be used forthe control unit 1040.

The control unit 1040 may recognize a user action, and may control thereception device 1000 on the basis of the recognized user action. Here,the user action may include selection of a physical button of thereception device, execution of a predetermined gesture or selection of asoft button on a touch screen display, execution of a predeterminedgesture that is recognized from an image captured by an image capturingdevice, and execution of predetermined vocalization that is recognizedthrough voice recognition. The gesture may include a touch gesture and aspatial gesture.

The transmission unit 1050 transmits data to another reception device.Here, the data may include at least one of a control signal, data, andinformation related to measurement report. The information related tothe measurement report may include information on the result ofmeasurement of the channel state. The data may be encoded to thecodeword to be transmitted.

FIG. 11 is a block diagram illustrating the configuration of a decoderaccording to a preferred embodiment of the present disclosure.

Referring to FIG. 11, a decoder 1030 may include an inner decoder 1110,a deinterleaver 1120, a binary decoder 1130, and an interleaver 1140.

The inner decoder 1110 may perform decoding using a reception channelLLR value that is calculated by the demodulation unit 1020 using a BCJRalgorithm using forward/backward recursion and a probability value ofthe codeword that is output from the interleaver 1140. The inner decoder1110 may use message values of the (j−1)-th and (j+1)-th symbol nodeswhen decoding the i-th symbol node. That is, the symbol node included inthe codeword may be decoded using the message values of symbol nodes infront and in the rear of the symbol node. According to the codeword thatis generated by the method for puncturing a codeword according to thepresent disclosure, non-punctured nodes are arranged in front and in therear of the punctured nodes during decoding, and the corresponding nodesreceive messages of high reliability from both sides thereof during thedecoding.

The deinterleaver 1120 deinterleaves the codeword decoded by the innerdecoder 1110.

The binary decoder 1130 decodes the codeword that is deinterleaved bythe deinterleaver 1120 and generates data. The binary decoder 1130outputs the codeword to the interleaver 1140.

The interleaver 1140 interleaves the codeword that is output from thebinary decoder 1130, and outputs the interleaved codeword to the innerdecoder 1110. Here, the interleaver 1140 may be the same as theinterleaver 220 located inside the encoder 110. Accordingly, the decoder1030 according to the present disclosure generates data by iterativelydecoding the codeword through the inner decoder 1110, the deinterleaver1120, the binary decoder 1130, and the interleaver 1140.

FIG. 12 is a flowchart illustrating performing processes of a method forgenerating a codeword according to a preferred embodiment of the presentdisclosure.

Referring to FIG. 12, the binary encoder 210 encodes data to a codeword(S100). The binary encoder 210 may encode the data using a binary code.The binary encoder 210 may receive the data from the control unit 140 inthe unit of a bit, and may generate the codeword through repetition ofall bits as many as a predetermined number of times. Here, the number ofrepetitions for each bit may not be uniform. The codeword that is outputfrom the binary encoder 210 may be a binary data stream. The binary codemay be an IR code.

The interleaver 220 interleaves the codeword that is encoded by thebinary encoder 210 (S110). The interleaver 220 may rearrange binary datastreams output from the binary encoder 210, and may tie up apredetermined number of binary data streams into a group. Further, theinterleaver 220 may output bit strings that are tied up into a group tothe inner encoder 230.

The inner encoder 230 inserts doping symbols into the codeword that isinterleaved by the interleaver 220 (S120).

The inner encoder 230 punctures the codeword into which the dopingsymbols are inserted (S130).

The modulation unit 120 modulates the punctured codeword (S140).

The transmission unit 130 transmits the codeword that is modulated bythe modulation unit 120 (S150).

FIG. 13 is a flowchart illustrating performing processes of a method forgenerating a codeword according to a preferred embodiment of the presentdisclosure.

Referring to FIG. 13, the inner encoder 110 calculates the number ofpunctured symbol nodes from the codeword (S200). Here, the codeword maybe a codeword that is output by the binary encoder 210 or theinterleaver 220.

The inner encoder 110 confirms whether the target code rate is smallerthan 2/3 (S210).

If the target code rate is not smaller than 2/3, the inner encoder 230performs basic puncturing (S220). Here, the inner encoder 230 puncturessymbol nodes located at even or odd number positions among symbol nodesincluded in the codeword. The symbol nodes to be punctured among thesymbol nodes located at even or odd number positions may be determinedon the basis of the locations of the doping symbols included in thecodeword.

The inner encoder 230 calculates the number of symbol nodes which needto be additionally punctured on the basis of the calculated number ofthe symbol nodes to be punctured (S230).

The inner encoder 230 determines the size of the punctured node group(S240). Here, the inner encoder 230 may determine the size of thepunctured node group on the basis of the number of symbol nodes whichneed to be punctured, and may classify the symbol nodes, which need tobe additionally punctured, into one or more punctured node groupsaccording to the determined size. As a partial embodiment, the innerencoder 230 may determine the size of the punctured node group on thebasis of at least one of the size and the number of symbol bands of thecodeword. Here, the symbol band means a set of a predetermined number ofconsecutive code symbols including one doping symbol. As a partialembodiment, the inner encoder 230 may classify the symbol nodes into oneor more punctured node groups on the basis of at least one of the sizeand the number of symbol bands of the codeword and the size of thepunctured node group determined according to a predetermined value. Thesizes of at least two punctured node groups among the one or morepunctured node groups may be equal to each other.

The inner encoder 230 determines the locations on the codeword where theone or more classified punctured node groups are to be arranged (S250).As a partial embodiment, each of the one or more punctured node groupsmay be arranged in the center of the symbol band of the codeword.Further, a plurality of punctured node groups may be arranged on atleast one of the symbol bands of the codeword. The number of puncturednode groups arranged on the symbol band may be determined on the basisof at least one of the doping symbol and the target code rate of thecodeword, and the number of punctured node groups arranged on at leastone of the symbol bands of the codeword may be different from the numberof punctured node groups arranged on another symbol band.

The inner encoder 230 punctures the symbol nodes included in thecodeword that belong to the punctured node groups according to thedetermined locations (S260).

If the target code rate is smaller than 2/3, the inner encoder 110punctures the symbol nodes included in the codeword so that thepunctured nodes are uniformly arranged on the codeword (S270). Thetarget code rate may be a code rate of the codeword that is output tothe modulation unit 120.

As a partial embodiment, operation S130 of FIG. 12 may includeoperations S200 to S260.

FIG. 14 is a flowchart illustrating performing processes of a method forgenerating a codeword according to another preferred embodiment of thepresent disclosure.

Referring to FIG. 14, the inner encoder 230 punctures the codeword at afirst target code rate (S300). Operation S300 may include operationsS200 to S260 of FIG. 13.

For conversion into a second target code rate, the inner encoder 230calculates the number of punctured nodes to be unpunctured in thecodeword punctured at the first target code rate (S310). The firsttarget code rate and the second target code rate may be different fromeach other, and the second target code rate may be higher than the firsttarget code rate.

The inner encoder 230 unpunctures the punctured nodes in the codewordaccording to the calculated number of punctured nodes (S320). Here, thepunctured nodes that belong to the punctured node group may be firstunpunctured.

As a partial embodiment, operation S130 of FIG. 12 may includeoperations S300 to S320 of FIG. 13.

FIG. 15 is a flowchart illustrating performing processes of a method fordecoding a codeword according to a preferred embodiment of the presentdisclosure.

Referring to FIG. 15, the reception unit 1010 receives the codeword fromthe transmission device 100 (S400). The codeword may include a controlsignal and data. The received codeword may be generated by puncturingsymbol nodes located at even or odd number positions among symbol nodesincluded in the codeword, classifying the symbol nodes, which need to beadditionally punctured, into one or more punctured node groups, andpuncturing the symbol nodes which belong to the punctured node groupsaccording to the locations on the codeword where the one or morepunctured node groups are arranged.

The demodulation unit 1020 demodulates the codeword received by thereception unit 1010 (S410).

The decoder 1030 decodes the codeword demodulated by the demodulationunit 1020 (S420). The decoder 1030 may decode the codeword using dopingsymbols included in the codeword. As an example, the doping symbol maybe used as information that helps an iterative decoder to operate. Here,the iterative decoder may be an iterative decoder of an IRPA code.

FIG. 16 is a graph illustrating the performance of a method forgenerating a codeword.

Referring to FIG. 16, a graph 1600 shows the performance of a puncturingpattern in which the codeword is encoded at a code rate of 2/3 in anAdditive White Gaussian Noise (AWGN) channel in the case whereinformation bits are 960, the modulation order is 16, and a dopingperiod is 30.

In the graph 1600, a curve 1610 indicates the performance of apuncturing pattern that is designed by a method (conventional method)for designing a puncturing pattern using the concept of a k-StepRecoverable node that is applied to the puncturing of an LDPC code, anda curve 1620 indicates the performance of a puncturing pattern that isdesigned so that the size of the punctured node group becomes 13 using amethod for generating a codeword according to the present disclosure asillustrated in FIG. 8.

Further, a curve 1630 indicates the performance of a puncturing patternthat is designed so that the size of the punctured node group becomes 25using a method for generating a codeword according to the presentdisclosure as illustrated in FIG. 8, and a curve 1640 indicates theperformance for the original codeword.

Through the graph 1600, it can be confirmed that the method 1620according to the present disclosure has improved the performance byabout 0.1 dB at the Frame Error Rate (FER) of 10^-2 in comparison to theconventional method 1610. Further, it can be confirmed that the method1630 according to the present disclosure has improved the performance byabout 0.2 dB at the Frame Error Rate (FER) of 10^-2 in comparison to theconventional method 1610.

Further, through the graph 1600, it can be confirmed that all the threemethods 1610, 1620, and 1630 do not generate an error floor up to theFER of 10^-3.

FIG. 17 is another graph illustrating the performance of a method forgenerating a codeword.

Referring to FIG. 17, a graph 1700 shows the performance of a puncturingpattern in which the codeword is encoded at a code rate of 5/6 in anAdditive White Gaussian Noise (AWGN) channel in the case whereinformation bits are 960, the modulation order is 16, and a dopingperiod is 30.

In the graph 1700, a curve 1710 indicates the performance of apuncturing pattern that is designed by a method (conventional method)for designing a puncturing pattern using the concept of a k-StepRecoverable node that is applied to the puncturing of an LDPC code, anda curve 1720 indicates the performance of a puncturing pattern that isdesigned so that the size of the punctured node group becomes 13 using amethod for generating a codeword according to the present disclosure asillustrated in FIG. 8.

Further, a curve 1730 indicates the performance of a puncturing patternthat is designed so that the size of the punctured node group becomes 25using a method for generating a codeword according to the presentdisclosure as illustrated in FIG. 8.

Through the graph 1700, it can be confirmed that the methods 1720 and1730 according to the present disclosure do not generate an error floorup to the FER of 10^-3.

Further, through the graph 1700, it can be confirmed that the method1730 according to the present disclosure has improved the performance byabout 0.5 dB at the Frame Error Rate (FER) of 10^-2 in comparison to themethod 1720 according to the present disclosure.

Meanwhile, preferred embodiments of the present disclosure disclosed inthis specification and drawings are illustrated to present only specificexamples in order to clarify the technical contents of the presentdisclosure and to help understanding of the present disclosure, but arenot intended to limit the scope of the present disclosure. It will beapparent to those skilled in the art to which the present disclosurepertains that various modifications may be made on the basis of thetechnical idea of the present disclosure in addition to the embodimentsdisclosed herein. The technical features disclosed in the respectiveembodiments disclosed herein can be embodied in combination with otherembodiments.

The invention claimed is:
 1. A method for generating a codeword,comprising: calculating a number of punctured symbol nodes among symbolnodes included in a codeword; puncturing symbol nodes located at even orodd number positions among the symbol nodes included in the codeword;calculating a number of symbol nodes which need to be additionallypunctured based on the calculated number of the symbol nodes to bepunctured; classifying the symbol nodes, which need to be additionallypunctured, into one or more punctured node groups based on thecalculated number of symbol nodes which need to be punctured;determining locations on the codeword where the one or more puncturednode groups are to be arranged; and puncturing the symbol nodes includedin the codeword which belong to the punctured node groups according tothe determined locations.
 2. The method of claim 1, wherein thecalculating the number of punctured symbol nodes comprises calculatingthe number of punctured symbol nodes among the symbol nodes included inthe codeword based on a current code rate and a first target code rateof the codeword.
 3. The method of claim 2, further comprising:calculating the number of punctured nodes to be unpunctured in thecodeword for conversion of the first target code rate into a secondtarget code rate; and unpuncturing the punctured nodes in the codewordaccording to the calculated number of punctured nodes, wherein thepunctured nodes that belong to the punctured node group are firstunpunctured.
 4. The method of claim 2, further comprising: confirmingwhether the first target code rate is smaller than 2/3; and if the firsttarget code rate is smaller than 2/3, puncturing the symbol nodesincluded in the codeword so that the punctured nodes are uniformlyarranged on the codeword, wherein if the first target code rate is notsmaller than 2/3, the symbol nodes located at the even or odd numberpositions are punctured.
 5. The method of claim 1, wherein the symbolnodes to be punctured among the symbol nodes located at the even or oddnumber positions are determined based on locations of doping symbolsincluded in the codeword, wherein sizes of at least two of the one ormore punctured node groups are equal to each other, wherein each of theone or more punctured node groups is arranged in a center of a symbolband of the codeword, wherein a plurality of punctured node groups arearranged on at least one of symbol bands of the codeword, wherein thenumber of punctured node groups arranged on symbol bands is determinedbased on at least one of a doping symbol or a target code rate of thecodeword, and wherein the number of punctured node groups arranged on atleast one of symbol bands of the codeword is different from the numberof punctured node groups arranged on another symbol band.
 6. The methodof claim 1, wherein the classifying the symbol nodes into the one ormore punctured node groups comprising: classifying the symbol nodes intothe one or more punctured node groups further based on at least one of asize and a number of symbol bands of the codeword; and classifying thesymbol nodes into the one or more punctured node groups further based ona size of the punctured node group that is determined according to apredetermined value.
 7. The method of claim 1, further comprising:encoding data; interleaving the encoded data; generating the codewordthrough insertion of doping symbols into the interleaved data;modulating the codeword; and transmitting the modulated codeword.
 8. Anapparatus for generating a codeword, comprising: an encoder configuredto calculate a number of punctured symbol nodes among symbol nodesincluded in a codeword, puncture symbol nodes located at even or oddnumber positions among the symbol nodes included in the codeword,calculate a number of symbol nodes which need to be additionallypunctured based on the calculated number of the symbol nodes to bepunctured, classify the symbol nodes, which need to be additionallypunctured, into one or more punctured node groups based on thecalculated number of symbol nodes which need to be punctured, determinethe locations on the codeword where the one or more punctured nodegroups are to be arranged, and puncture the symbol nodes included in thecodeword which belong to the punctured node groups according to thedetermined locations; and a transmission unit which transmits thecodeword.
 9. The apparatus of claim 8, wherein the encoder is configuredto calculate the number of punctured symbol nodes among the symbol nodesincluded in the codeword based on a current code rate and a first targetcode rate of the codeword.
 10. The apparatus of claim 9, wherein theencoder is configured to calculate the number of punctured nodes to beunpunctured in the codeword for conversion of the first target code rateinto a second target code rate, and unpunctures the punctured nodes inthe codeword according to the calculated number of punctured nodes, andwherein the punctured nodes that belong to the punctured node group arefirst unpunctured.
 11. The apparatus of claim 9, wherein the encoder isconfigured to confirm whether the first target code rate is smaller than2/3, puncture the symbol nodes included in the codeword so that thepunctured nodes are uniformly arranged on the codeword if the firsttarget code rate is smaller than 2/3, and puncture the symbol nodeslocated at the even or odd number positions if the first target coderate is not smaller than 2/3.
 12. The apparatus of claim 8, wherein thesymbol nodes to be punctured among the symbol nodes located at the evenor odd number positions are determined based on locations of dopingsymbols included in the codeword, wherein sizes of at least two of theone or more punctured node groups are equal to each other, wherein eachof the one or more punctured node groups is arranged in a center of asymbol band of the codeword, wherein a plurality of punctured nodegroups are arranged on at least one of symbol bands of the codeword,wherein the number of punctured node groups arranged on symbol bands isdetermined based on at least one of a doping symbol or a target coderate of the codeword, and wherein the number of punctured node groupsarranged on at least one of symbol bands of the codeword is differentfrom the number of punctured node groups arranged on another symbolband.
 13. The apparatus of claim 8, wherein the encoder is configured toclassify the symbol nodes into the one or more punctured node groupsfurther based on at least one of a size or a number of symbol bands ofthe codeword, and wherein the encoder is configured to classify thesymbol nodes into the one or more punctured node groups further based ona size of the punctured node group that is determined according to apredetermined value.
 14. The apparatus of claim 8, wherein the encodercomprises: a binary encoder configured to encode data; an interleaverconfigured to interleave the encoded data; and an inner encoderconfigured to generate the codeword through insertion of doping symbolsinto the interleaved data, wherein the inner encoder is configured tocalculate the number of punctured symbol nodes among symbol nodesincluded in the generated codeword, puncture symbol nodes located ateven or odd number positions among the symbol nodes included in thecodeword, calculate the number of symbol nodes which need to beadditionally punctured based on the calculated number of the symbolnodes to be punctured, classify the symbol nodes, which need to beadditionally punctured, into one or more punctured node groups based onthe calculated number of symbol nodes which need to be punctured,determine the locations on the codeword where the one or more puncturednode groups are to be arranged, and puncture the symbol nodes includedin the codeword which belong to the punctured node groups according tothe determined locations.
 15. The apparatus of claim 8, furthercomprising a modulation unit configured to modulate the codeword,wherein the transmission unit transmits the modulated codeword.
 16. Amethod for recovering a codeword, comprising: receiving a codeword,wherein the received codeword is generated by puncturing symbol nodeslocated at even or odd number positions among symbol nodes included inthe codeword, classifying the symbol nodes, which need to beadditionally punctured, into one or more punctured node groups, andpuncturing the symbol nodes which belong to the punctured node groupsaccording to the locations on the codeword where the one or morepunctured node groups are arranged; demodulating the received codeword;and decoding the demodulated codeword.
 17. The method of claim 16,wherein the decoding comprising: decoding the demodulated codeword usingdoping symbols included in the codeword; and performing a Bahl CockeJelinek Raviv (BCJR) algorithm using forward/backward recursion, whereinthe symbol node included in the codeword is decoded using message valuesof symbol nodes that are in front and in the rear of the symbol node.18. A receiver comprising: a reception unit configured to receive acodeword; a demodulation unit configured to demodulate the receivedcodeword; and a decoder configured to decode the demodulated codeword,wherein the received codeword is generated by puncturing symbol nodeslocated at even or odd number positions among symbol nodes included inthe codeword, classifying the symbol nodes, which need to beadditionally punctured, into one or more punctured node groups, andpuncturing the symbol nodes which belong to the punctured node groupsaccording to the locations on the codeword where the one or morepunctured node groups are arranged.
 19. The receiver of claim 18,wherein the decoder is configured decode the demodulated codeword usingdoping symbols included in the codeword.
 20. The receiver of claim 18,wherein the decoder is configured decode the codeword through performingof a Bahl Cocke Jelinek Raviv (BCJR) algorithm using forward/backwardrecursion, wherein the symbol node included in the codeword is decodedusing message values of symbol nodes that are in front and in a rear ofthe symbol node.